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quality problems when encoding to H.264
Hello,
I have observed that my mp4 files have sometimes regions of poor quality (especially in low-contrast regions): the texture is jumping every 1-1.5 seconds or so. Could somebody please explain what can be improved here?
I am using ‘Render at Maximum Depth’, ‘Use Maximum Render Quality’, VBR 2pass with target bitrate of 14 Mbps.
Thank you
Daniel -
3 Replies
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are you using the Quicktime then H.264 (under that) on export settings?
or H.264 then the preset under it?I had quality problems as well, but i was using the quicktime wrapped
h.264 and that was the problem. -
Hi Daniel,
You are describing key frames. Just as a refresher, in the compression world key frames are complete frames, every other frame only contains changed pixels from the previous frame.
Those changes become less and less accurate as you drop bit rate and /or increase resolution, and it prioritizes lighter areas since that’s where it will be most noticeable. Every time you hit a keyframe you will see a sort of jump when all the pixels are refreshed.
So, the easiest solution is simply to increase your bitrate.
You can also change the key frame frequency in your settings. If you increase the frequency, you may see less of a “jump”, but you will decrease the overall quality.
Vince Becquiot
San Francisco Bay Area
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Hello,
Thanks a lot, that was my suspicion as well. When trying to increase keyframe rate, quality got worse, as you say, so I got disappointed. And I probably did not increase the bitrate enough. I will play with that, thanks a lot.
Daniel
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